"Anarchist" is applied here to two different kinds of entries, and they are not equally secure. Some rows describe groups that used the word for themselves — the CNT-FAI, Makhno's insurgents, the Korean Anarchist Federation in Manchuria. Others are retrospective attributions by historians or anthropologists to societies that organized without a state but never used the term — the Icelandic Commonwealth, highland Southeast Asia as described by James C. Scott, Rojava's democratic confederalism. Rows of the second kind are marked retro. Conflating the two risks reading a modern ideology into contexts that had their own, different, self-understanding.

Population figures for pre-20th-century and wartime entries are frequently the least reliable numbers in any historical record, and estimates here come from a mix of academic and partisan sources that do not agree with each other; treat every number under "population" as an order of magnitude, not a count. The Free Territory's 7.5 million and the Spanish collectives' 5–7 million peasants, in particular, describe people living under or affected by these arrangements, not committed participants.

Omissions worth naming: this register leans toward incidents documented in English-language sources, which underweights African, South Asian, and pre-colonial Latin American cases that anarchist historiography has only partially recovered. It also excludes purely organizational or insurrectionary episodes that never held territory (the First International's anarchist wing outside the Jura Federation, Haymarket, most propaganda-by-deed actions) since the brief asked for enclaves and systems, not events.